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Week 6: Conservation and Protection Efforts for Sharks and Rays
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Did you know... shark skin, or shagreen, feels rough if you stroke it in one direction (back to front), but smooth if you stroke it in the other (front to back)? Shark skin is covered with modified scales, known as dermal denticles, which contribute to their superb hydrodynamics. Fabric for high-tech racing swimsuits, seen in recent Olympic competition, has been modeled after it as this design reduces drag and turbulence. |
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The idea that sharks don't get cancer seems to stem from scant clinical evidence that cartilage has antiangiogenic properties--i.e., it inhibits the development of blood vessels, which are crucial to the growth of cancerous tumors--and since shark skeletons are made of cartilage, it follows (albeit somewhat loosely) that they can't get cancer. Recent studies and literature reviews have found that while the incidence of cancer in sharks and related fishes such as rays does seem to be low, cancerous tumors, including chondromas (cancers of the cartilage), have in fact been found in sharks. The reasons for the apparently low incidence are not necessarily related to their high cartilage content, but may simply be a matter of lack of directed research on cancer in sharks and related fishes. While cartilage may have antiangiogenic properties, orally ingesting powdered shark cartilage has not been shown to be an effective cancer treatment or prevention, because none of the constituent parts of the powder appear to be absorbed across the intestine wall into the bloodstream. Besides the lack of evidence that shark cartilage prevents or cures cancer in humans, the fishing of sharks for manufacturing shark cartilage products endangers shark populations and upsets fragile marine ecosystems. The myth that "sharks don't get cancer" is thus both a medical fallacy and results in the pointless slaughter of sharks, jeopardizing the existence of the species. See also:
The Truth About The Shark Cartilage Scam
Study Debunks Shark Cartilage Cancer Cure | ||||||||||||||
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